Our research investigates the cell and molecular biology of photoreceptors and their associated extracellular matrix. This research will develop the biomedical research skills of the participating MBRS students. They will be involved in every aspect of the research including the planning, execution, and evaluation of experiments. They will also attend meetings to present their findings and be co-authors on resulting publications. Our specific aims include new direction in our research as well as new investigations of areas that are of continuing interest. We will specifically address the following issues using octopus retina as our model system. 1. The expression of specific retinal mRNAs in photoreceptor development. Using in situ hybridization and immunocytochemical techniques we will determine when the genes for two specific proteins are first expressed in the developing octopus retina. We will also use radiobiochemical and autoradiographic methods to determine if a functional visual pigment is present early in photoreceptor development. 2. LSCM investigation of the chromophore shuttle mechanism in cephalopods. Retinal binding protein shuttles chromophore from the myeloid bodies to the rhabdomes. We will use the Laser Scanning Confocal Microscope to investigate this shuttle mechanism and will compare the distribution of RALBP, rhodopsin and retinochrome in light and dark adapted retinas. 3. Characterization of the interphotoreceptor matrix in adult and embryonic octopus retinas. Biochemical and immunocytochemical techniques will be used to further identify the molecular constituents of the IPM in adult and developing octopus retinas. Lectin binding studies will establish the presence and identity of glycoconjugants in the IPM of retinas from early stages of development through hatching. 4. Identification of an RBP-like gene in octopus. Molecular techniques will be used to identify the gene for octopus serum retinol-binding protein (ORBP). These studies will establish a base for continuing molecular studies on octopus retinoid transport.